From: Vasily Averin <vvs@virtuozzo.com>
To: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>,
Anna Schumaker <anna.schumaker@netapp.com>,
kernel@openvz.org, linux-nfs@vger.kernel.org,
linux-kernel@vger.kernel.org,
Chuck Lever <chuck.lever@oracle.com>
Subject: Re: [PATCH v3 2/3] nfs4: handle async processing of F_SETLK with FL_SLEEP
Date: Sun, 16 Jan 2022 15:25:43 +0300 [thread overview]
Message-ID: <b332a1dd-f96d-2d83-80ca-67058eeaa1af@virtuozzo.com> (raw)
In-Reply-To: <20220103194012.GF21514@fieldses.org>
On 03.01.2022 22:40, J. Bruce Fields wrote:
> On Wed, Dec 29, 2021 at 11:24:43AM +0300, Vasily Averin wrote:
>> nfsd and lockd use F_SETLK cmd with the FL_SLEEP flag set to request
>> asynchronous processing of blocking locks.
>>
>> Currently nfs4 use locks_lock_inode_wait() function which is blocked
>> for such requests. To handle them correctly FL_SLEEP flag should be
>> temporarily reset before executing the locks_lock_inode_wait() function.
>>
>> Additionally block flag is forced to set, to translate blocking lock to
>> remote nfs server, expecting it supports async processing of the blocking
>> locks too.
>
> Seems like an improvement, but is there some way to make this more
> straightforward by just calling a function that doesn't sleep in the
> first place? (posix_lock_inode(), maybe?)
There are few problems:
1) posix_lock_inode() is static in fs/locks.c
2) exported posix_lock_file() used posix_lock_inode() inside requires file pointer,
and I do not understand how to get it.
3) _nfs4_do_setlk() is called from do_setlk and handles flocks too,
therefore any posix-only calls requires additional checks or branches.
On the other hand all that is required to handle F_SETLK with FL_SLEEP correctly :
to avoid blocking on exiting lock. We can reach this goal here by drop of FL_SLEEP flag
before locks_lock_inode_wait() execution.
Thank you,
Vasily Averin
PS I'm worry for a long delay with answer,
in Russia we have long holidays after New Year,
then I dealt with urgent tasks accumulated over the holidays
then I forgot the context of this patch and
I was need to spend some time to re-member the details.
>> https://bugzilla.kernel.org/show_bug.cgi?id=215383
>> Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
>> ---
>> fs/nfs/nfs4proc.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
>> index ee3bc79f6ca3..9b1380c4223c 100644
>> --- a/fs/nfs/nfs4proc.c
>> +++ b/fs/nfs/nfs4proc.c
>> @@ -7094,7 +7094,7 @@ static int _nfs4_do_setlk(struct nfs4_state *state, int cmd, struct file_lock *f
>> recovery_type == NFS_LOCK_NEW ? GFP_KERNEL : GFP_NOFS);
>> if (data == NULL)
>> return -ENOMEM;
>> - if (IS_SETLKW(cmd))
>> + if (IS_SETLKW(cmd) || (fl->fl_flags & FL_SLEEP))
>> data->arg.block = 1;
>> nfs4_init_sequence(&data->arg.seq_args, &data->res.seq_res, 1,
>> recovery_type > NFS_LOCK_NEW);
>> @@ -7200,6 +7200,9 @@ static int _nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock
>> int status;
>>
>> request->fl_flags |= FL_ACCESS;
>> + if (((fl_flags & FL_SLEEP_POSIX) == FL_SLEEP_POSIX) && IS_SETLK(cmd))
>> + request->fl_flags &= ~FL_SLEEP;
>> +
>> status = locks_lock_inode_wait(state->inode, request);
>> if (status < 0)
>> goto out;
>> --
>> 2.25.1
next prev parent reply other threads:[~2022-01-16 12:25 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-27 10:45 [PATCH] nfs4: handle async processing of F_SETLK with FL_SLEEP Vasily Averin
2021-12-27 15:51 ` [PATCH v2] " Vasily Averin
2021-12-28 1:04 ` Vasily Averin
2021-12-29 8:24 ` [PATCH v3 1/3] nfs: local_lock: " Vasily Averin
2021-12-29 8:24 ` [PATCH v3 2/3] nfs4: " Vasily Averin
2022-01-03 19:40 ` J. Bruce Fields
2022-01-16 12:25 ` Vasily Averin [this message]
2022-01-03 19:53 ` J. Bruce Fields
2022-01-16 12:44 ` Vasily Averin
2022-01-16 18:28 ` Vasily Averin
2022-01-18 22:35 ` J. Bruce Fields
2021-12-29 8:24 ` [PATCH v3 3/3] nfs v2/3: nlmclnt_lock: " Vasily Averin
2021-12-27 17:58 ` [PATCH] nfs4: " kernel test robot
2022-01-06 10:37 ` Dan Carpenter
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